I've been looking over a few bagel recipes here and elsewhere and I'm rather stunned at the varying amounts of time I've seen recommended for the boiling stage. Everything from 5 seconds to 7 minutes has been suggested. I've seen one minute per side a little more often but the vast differences seem to be puzzling. So I thought I'd ask the experts here the following:

A) What is the aim of the boiling stage

B) How long do the bagels actually need to boil to attain that aim?