"SUPER"
'(<a href="http://www.j-archive.com/media/2011-07-13_J_06.wmv">Sarah of the Clue Crew demonstrates the clue with a plastic bottle of water.</a>) Pure water can remain liquid below the freezing point because there are no impurities to form ice crystals around, a phenomenon called this. Motion causes bubbles, allowing the water to crystallize.'
supercooling