Mine was the upper control arm bushings but it could be a long list of issues.
1. bushings
2. bearings
3. skid plate bolts
4. idler or pitman arm play
5. ball joints


just take the time to jack it up and shake down the front end. most likely you will be able to identify the issue if its a bushing, bearing or front end component. if its not then most likely its the skid plate flexing.

 

Mine got a pop sound , more like while driving @~50 .. got me crazy for a few weeks ,tried a few things but nothing seems to work, after replacing the shocks noise is gone ...
Btw check also the hub for any movement