I hope that this is a fun question for you physicists to answer.
Say you had a perfect piston - its infinitely strong, infinitely dense, has infinite compression ... you get the idea. Then you fill it with some type of matter, like water or dirt or something. What would happen to the matter as you compressed it indefinitely?
Edit: I'm getting some responses that it would form a black hole. For this question I was looking for something a little deeper, if you don't mind. Like if water kept getting compressed would it eventually turn into a solid, then some sort of energy fireball cloud? I'm not as concerned about the end result, black hole, as I am in the sequence.