My Japanese Fender P did this, and I found out that static was building up on the pickguard and discharging causing the pops. I knew it must be from the pickguard, because it would also make hissing sounds if I rubbed the pickguard with my fingers in the area between the pickup and volume knob. I read about the dryer sheet solution, but also read that it was only a temporary solution. So I got a large single piece of self adhesive copper foil from a stained glass shop and covered the entire back of my pickguard (just to be safe, lol), and I’ve never had any of those noises again. If you do decide to shield the back of the pickguard, make sure the copper foil goes under the pots and jack for continuity.