Paint which sits around on the shelf for a while will do that...and it doesn't take that long. Especially today. I've posted here before that today's "enamel" is actually a closer kin to yesterday's lacquer if you analyze the ingredients. The manufacturers do that to make it dry faster I suspect. My suggestion: when you get it home, set it upside down in the sun and leave it there for a day. Then turn it upright and shake it for several minutes...5 or so at least. Then set it on one side and repeat the process. Bake in sun a while and then shake the tar out of it. Do this again if you feel like it. What is happening when paint clogs and starts spitting is very simple. The paint has been sitting there and it has separated. The heavy bits settle to the bottom and coagulate. They don't get mixed well enough before you start to spray and then you suck some of them up into the feed tube...where they stay forever. From there some globs will make it all the way up to the release valve and if that happens the only option is to try to get the paint out of there. Here is one very dangerous and generally ill-advised way: Hold the can upside down, let all the paint run down and very very carefully use a pointed tip can opener to make a tiny hole in the bottom of the can where the air can be released completely. Hold a junk towel over the bottom so you don't get a bath or get injured...but please just make a tiny hole. Then you can drain the paint out, mix it well and pour it into a PreVal jar (
https://preval.com/) and have a chance at spraying it. You may have to study the maker's ingredient list to see what the main solvent used was. You may add a tiny bit of that to help thin the paint a bit if needed. Good luck!
PS neither your mother, your father, any of your sensible and semi-grade-school educated friends or even people who may not like you very much are likely to suggest my paint draining method. So yes, it could injure you badly or something. It could leave you painted canvas white. It could blind you or cause all your children to be born naked and all sorts of things. I can't take responsibility for anything at all pretty much in the entire world, so you're on your own. Once upon a time paint was made so that if you turned the can upside down and pressed the spray button only the air would come out but those days are gone now.
Edit: just checked and acetone seems to be the main solvent.
