Have you ever watched a pot of water waiting for it to boil? You know, you're in a rush and trying to cook dinner and have to wait for the water to boil first. So you start the pot, and then sit there waiting. And no matter how much you try to distract yourself to let the time pass, you come back and the pot still hasn't started boiling?

So you sit there and wait. And you know the pot is just about to start boiling. You can see the tiny bubbles forming on the bottom. Steam has started to rise off the water, but it's not quite at the boiling point...