Hot ice, scientifically known as sodium acetate, is a liquid that will turn solid at the slightest provocation. Touching it with your finger or bumping it too hard will cause it to spring from a clear, water-like state into solid ice-like crystals.
For camping or late nights at the beach? Leave 1/4 of Mountain dew in bottle (just dont drink it all), add a tiny bit of baking soda and 3 caps of peroxide. Put the lid on and shake - viola! Homemade glow stick (bottle) solution. So cool!