Sniper Elite V2

*Only Grenades, Trip Mines, Land Mines and Dynamite count towards the achievement. Blowing up barrels, vehicles or any other type of "explosive" will count for an explosive kill, but it will not count towards the achievement.*

An easy way to "grind" this achievement is on the second to last mission called "Kopenick Launch Site". Right at the beginning of the mission there will be two enemies in front of you. One is walking forward and the other one is laying on the ground. Just throw a frag in the center of them and it will blow both of them up. Rinse and repeat until you get 100 explosive kills. You can check your stats in the Extras Menu of the game.

Here's a video guide to show you:

The best location to farm 100 kills quickly is in Mission 4 - Kaiser-Friedrich Museum. After obtaining the Mosin Nagant you will exit a building and see four Russians standing close together at the end of a street. One of them will have a grenade on his webbing. Shoot the grenade and all four soldiers will get killed. Each one counts towards this trophy / achievement. Restart the checkpoint (it will keep your kill statistics!) and repeat the process over and over again. If you start with 0 explosive kills you should be done after 15 minutes. This should automatically earn you the 'Cooking Off' achievement.

To clarify, only equipment explosions count. Trip mines, land mines, grenades and dynamite are the requirements for this achievement.

So if you get a kill while blowing up a vehicle, it is technically an "explosive" kill. But it will NOT count towards the achievement.

Just grind away with the equipment! I am on my second playthrough on the campaign (played on Sniper Elite difficulty first and only had about 35 explosive kills) and I have it set on Cadet difficulty. You can literally walk up to enemies and heave grenades at them.

EDIT: I have exactly 100 explosive kills with equipment. 47 grenade kills, 20 trip mine kills, 24 land mine kills and 9 dynamite kills.

if anyone says that blowing up vehicles or shooting gas tanks and getting kills adds to this achievement, they are lying!

EXCELLENT GUIDE for the potato masher achievement, shows you where you can farm 100 kills on level 4 of this very good game, as you can tell i need 25 words so that should just about do it, enjoy the video and if you negative please say why, thankyou.

Go to Karlshorst Command Post, destroy the tank. Once you have done this, go plant a trip mine in front of the door that you are going to go through once you have killed every enemy. (next to the two MG-nests)

You'll get a checkpoint, quickly plant a land mine. One both of them blow up, plant another land mine. Then restart the checkpoint until you have your achievement!

Make sure to stack up on land mines and trip mines before you start the mission.

The above methods may be good, I didn't want to deal with the Launch site and only get one or 2 kills then restart, I chose the last mission Brandenburg Gate on Cadet difficulty. This method would get between 5-8 kills, with at least 3 guaranteed in about 30 seconds.

As the map starts you can sprint out the door and veer northeast (if standing in the doorway faces North) towards a metal "X" (by the car before the subway stairs), the placement is just so you can see one of the guards by the tent, throw a F1 grenade and if you got it between them you will get the 2 for 1 kill. Then from the metal X walk right to the stairs and throw a F1 into the 2nd story building for the guard watching behind the tent (upper left side if you are standing at the top of the subway stairs, you can just bounce it off the wall, you do not have to wait until you can see him). This is your 3 kills and takes a matter of seconds.
After the 3rd kill one guard, sometimes two will go and investigate the bodies of the first two you killed, throw a grenade near him/them and get those kills. At this point you can throw grenades at any guys shooting. In the tent is an ammo supply with two F1 Grenades and one Stielhandgranate, If you have any grenades left, run up the street to the emplacements and hide behind the trucks and kill what you can. I would purposely die and restart.
This method is probably quicker if you just want to restart after the 3rd kill, but I had about 50 kills so I only had to do this 7-8 times. Otherwise if you start from zero this 3 kill method is what you use you would do it 34 times, the launch site you would have to do it at least 50 times (depending on if you got the 2nd guy).

Mission: Kaiser-Friedrich Museum

Shortly after re-entering a building and going down a set of stairs, a new objective appears: Retrieve the munitions from the nearby park.

Immediately after a checkpoint you hear two Russkies having a conversation. Place dynamite in the middle of the room after the stairs. Shoot the dynamite. Immediate 2 for 1. Rinse, repeat until 100 kills.

Note: This is shortly before obtaining the Mosin Nagant.