@curious aardvark, I have some filament I purchased from a local Craigslist advert. Five bucks a kilogram and almost all of it was as much as five years old. The zipper seal bags were abraded, no protection from humidity in that respect. It prints horribly if I forget to dry it, but once dry, does a decent job. No popping though. Only my PVA has done that.

I agree that much more information is needed, otherwise it's all guesswork.