sounds like the water was too hot! lol. Best thing you can do, get a tupperware bowl, fill it up maybe an inch or two of lukewarm water (not too much that he will float, up half way on his back. and it will feel cool to you), put him in the tupperware, put in washcloth, put whole thing in his tub. Let sit for an hour, pull him out and assist him by letting him slide through the wash cloth. It should slide right off.

Edit: Dont suffocate your snake, make sure the enclosure is large enough for him to move easily, and have a top on too. If it really is a tupperware, they have a little pop top hole for when you reheat food. That should work too.