Yes it is very short-lived, but you can get an extra gig out of a dull set if necessary. It doesn't work a second time!
I don't boil strings any more, as I'm an Elixir user, but when I did I put a few drops of washing-up liquid in the water -- careful of the suds, it goes mad -- and waited till the water was at a good rolling boil before putting the strings in and turning the heat right down. 10 or 15 minutes is all that's needed.
Do NOT, whatever you do, make the same mistake as a friend of mine did... become engrossed in a TV programme and completely forget they're on the stove, and allow them to boil dry. It scorched the bottom of the nice stainless pan and the marks have never come off, not matter how hard he scrubbed, and my errm I mean his wife will never let him forget it.