Popping noise - bushings or brakes?

[BigRed]

I have had a popping noise on my suburban since I bought it about 3 months ago. It's in the front end. It happens the first time I hit my brakes in drive after I just was in reverse and hit the brakes.

As I mentioned, it only happens once. Also, I sometimes here it when I hit the brakes in reverse. But it always only happens once.

Does this sound like a brake problem, a worn bushing, or something else? How do I check my bushings to see if they are worn or not (other than visible inspection)?

Thanks!