Front end makes popping sound only when it's hot outside?

I drive a 1998 Ford Ranger and have an interesting question. The front end (related to the suspension?) makes popping/creaking sounds when it’s hot outside. I don’t have to be going over bumps, but I do have to turn the radio off to hear it. I’m planning on getting ball joint(s) replaced anyway, so is there something else I should have the mechanic check that might be related to this sound? Thanks!

If you already suspect bad balljoints, have the entire front suspension checked. As sson as possible. The balljoint replacement may do the trick, or there may be something else wrong. Perhaps something dangerous.