Oh also to answer the other question, sometimes snakes will try to clear their noses if they got water in it so they will sneeze, wheeze a bit, or make that popping/clicking noise when the exhale. Normally this happens when they dipped their head underneath the water when soaking or they may catch some water in their nose if you are bathing them.
Also, when they shed are in they may also make popping/clicking noises, and if they have a stuck shed in their nose they will make those noises, too.