Posted: Jun 26, 2012 3:43 pm
I've heard of the effect but never experimented to check it out. I'm going to throw my uneducated mind into the fray and postulate that in heated water the atoms are more loosely spaced (less bonded hydrogen/oxygen atoms) and as in order to freeze, water assumes a uniform structure (hence why it expands when frozen) that the atoms may be more "free" to assume this structure under rapid cooling than the more closer bound atoms in cool water.