When water wants 2 boil,it starts from under but if it wants 2 freezes it starts from d top.I really want 2 know why?all gurus,intellectuals,genius in the house,its time 2 brainstorm n provide clear,logical n simple answer 2 dis phenomenom.

VERY SIMPLE:

When temperature decreases, the bonding of the water molecule (also called hydrogen bond) becomes strong and prevents the molecule from contracting or shrinking. At 4°C the molecules begin to arrange themselves along the directional lines of the bond, leaving gaps or openings between these bonds. When the
bonds are formed, air is trapped between the molecules. Solid water has greater volume, and less density, than liquid water so it will automatically float and therefore freeze on top.

as for boiling water, the source of the heat is from the bottom so there you have it.