A friend of mine had a hotplate and he didn't like to clean his pots and pans, so he would often heat canned food by just placing the unopened can in boiling water. I don't recommend this because it's easy to burn yourself opening the hot can. One day I came over to visit and he'd left a can of ravioli on too long and it had exploded. It wasn't a pretty sight. I helped him clean the ravioli off the ceiling.