How to thaw a bottle of beer that got frozen accidentally without exploding the bottle
I've had the same experience as you, with beer and other liquids frozen in glass bottles.  Whenever I try to rapidly thaw them, it seems the structure of the glass is compromised in some way and it either explodes or cracks - this even has happened to me when trying to slow thaw, like you did.  

Beer bottles, and especially cans, can explode in the freezer and will make an ungodly mess.  Beer bottles exploding in the freezer are rare, but I've heard anecdotal stories from people I trust who said it has happened to them, perhaps with improper bottling and not enough room for expansion in the neck.

Since a few bad experiences with forgetting things in the freezer (I had an aluminum can of Hawaiian Punch literally explode all over the freezer one night, that was a MESS) I now only use the salted ice bath method!

I have tasted beer that was frozen and thawed without any glass shards in it, specifically a can of beer that partially exploded (I guess I didn't learn my lesson from the Hawaiian Punch that quickly).  It had enough left frozen in the bottom of the can that I figured I should thaw what was left, and give it a taste.  It wasn't bad, but it tasted a little...flatter than normal, I guess?  It just wasn't as full flavored as I expected.  Definitely a noticeable difference to me.