Omi said: Well, it's not actually the water that's burning. I'm no scientist 
but I'm pretty sure the batteries have left something of an acidic residue on the surface of the water, that would be what's burning. Again though, I have no clue, I'm just guessing
You're right... I think.
The title: Water Can Burn is all wrong.
If you tried to light water on fire, it wouldn't work but with some added chemicals it burns the chemicals, not the water.