When you cool water down it shrinks until it gets to about 4° C, then it starts to expand, when it solidifies as ice at below 0°c it has expanded so much that it floats on liquid water.
Water would boil at room temperature in a vacuum, it is the air pressure that decides the boiling point of water.
You can break water molecules with two wires and a 9 volt battery. When a certain amount electricity passes through water, it causes the oxygen and hydrogen bonds to break, this would cause oxygen and hydrogen gas to bubble at the surface.
The alkaline metals Lithium, Potassium and Sodium float on water, they also react with the water causing a release of hydrogen gas.
