Can someone explain the chicken-salt trick thing?

I know of, and have done many times, this method of baking a chicken (whole) in a mountain of salt (the chicken is not touching the salt, just sits in a crater in the middle). It always come out amazingly crispy on the outside and wonderfully juicy inside, with a real rotisserie flavour.

BUT HOW DOES IT WORK??

My guess is that the salt somehow creates a super hot environment around the chicken or something, but I am very curious as to what is really going on.

Can you explain this magic?