How do I earn the "Creamed corn" achievement?

In The Cave there are 2 cans of corn that you find during your journey: the first one at the Miner's puzzle and the second hidden behind a crate on the Island.

I tried everything that came to my mind with them: blowing the miner's one with dynamite (it's easy, just leave the can where it stands and the miner will throw a stick at it), jumping with the island one in the volcano, getting drowned with them, and many other creative ways to try and get this achievement.

What am I missing? What am I supposed to do?

You did right with the first one. This is how you do them both:

The first one is really easy. You can find the can of corn in the miner's puzzle. The miner throws three objects at you (shovel, bucket and can of corn). Then, he throws dynamite at you. It suffices that he throws a dynamite at his own can of corn to get it destroyed (the can looks different an even the description says it's destroyed - that's how you can see that it worked).

Now, the other can is a bit more tricky. It is on the last puzzle on the lonely island. The can is behind that blue box all to the right (and also some crackers). You have to take that can and place it somewhere near the exploding barrels in the volcano, so that the explosion destroys the can of corn in the process.

Source: Creamed Corn Achievement

From ps3trophies.org: In the section where you have to set off a chain reaction with exploding barrels, place the can next to the barrel beneath the rock that holds the water and light the first barrel. The explosion will destroy the can.