Why does a microwave heat the bottom of things?

[XZeroII]

If I were to put some hamburger into the microwave to defrost it quickly and pull it out 3/4 of the way through, I notice that the top of the package is still cold and partially frozen while the bottom is starting to cook. Why does the bottom cook?

 

[bunker]

Total guess here.

Microwaves seem to heat the liquid within an item. Defrosting a chunk of meat causes liquid to form at the bottom.

 

[Heisenberg]

Originally posted by: bunker
Total guess here.

Microwaves seem to heat the liquid within an item. Defrosting a chunk of meat causes liquid to form at the bottom.

More specifically, microwaves heat water molecules.

 

[loup garou]

Originally posted by: bunker
Total guess here.

Microwaves seem to heat the liquid within an item. Defrosting a chunk of meat causes liquid to form at the bottom.

That's what I was going to say.