In fact it is even possible to supercool water to below minus 30 degrees
centigrade.  The supercooled liquid is extremely unstable, and the tiniest
nudge causes an explosion of ice crystals.  One may find supercool water
and other fluids in nature.  For instance, the blood of hibernating arctic
squirrels may supercool to minus 3 degrees, when it would normally congeal.
The supercooled blood still flows, since it remains a liquid, but the
slightest disturbance may cause it to freeze, killing the squirrel;
therefore, you should not disturb hibernating arctic squirrels.

		-- João Magueijo, "Faster Than The Speed Of Light" (2003)