Why does water freeze?
The reason water freezes is that as heat energy leaves the water, the water molecules move more slowly. Ice crystals begin to form a solid lattice with higher cohesion between molecules. If the ice is reheated, it will lose its lattice structure and resume liquid form.
Warm water will not freeze faster because it will first need to cool and then freeze. If you take a two samples of water and boil sample A, let it cool so that both sample A and B are at the same temperature and then put them in the freezer, the boiled water (sample A) will freeze faster. Also, if you have tap water and purified water, the purified will freeze faster.