I’ve had that happen in the past with flat finish, quick drying paints. Most of the paints I’m trying to save are acrylic, glossier types and most often, car touch up paints. I can spray some into the cap and it will remain liquid for a few minutes, long enough to fill nicks in the paint. If it dries, I just dispense more.
I don’t throw paint cans in the trash unless they are punctured. If I want to dispose of them, I invert the can and push the button until all the propellant is removed. Then punch a hole and let the paint drain out and dry. It’s then safe for our trash pickup.
Some moron in the neighborhood threw half empty paint cans in the trash. They opened up when crushed and spilled from the truck. There were red streaks all down the road for a year. Some type of automotive paint so it was very persistent…