i've boiled many pipes, and the've never broken...but your house will smell like resin real bad after. If you can get pipe/bong cleaner, that works really well to.
use sudsy ammonia, 50/50 w/ hot water, and use a pin to 'touch' any part of the resin that's still caked on. it should be easy to knock off. just bend the pin around a bit to the spots that need it.
Isn't there something that you can just soak it in that will dissolve the ressin? I can't remember exactly what it is called, propenal something or other?