I had the stabilizer bushings go bad on me before. Popping was just one of the noises the car made. Otherwise it could be the ball-joint, the strut, strut mount, or as previously stated, the end link, though I have diffuculty with that; in my experience, my car just wallowed around ( 'course it also had a bad tie rod end, too!
).
Thinking about it, it sounds like a ball-joint or control arm bushing (ahah! almost forgot that!), but I'd wager on the former. You can get ball-joints separately, but it's usually worth your while to get the whole control arm assembly. You should just be able to jack up the car (with the jack under the arm), take a suitable bar, stick it under the tire and lift up. If the joint is bad, you'll know in a big big hurry.
