The other day, I heard a pop from underneath the passenger side when pulling forward at a slight turn in a parking lot. I haven't heard it again but occaissionally hear a clank sound over certain bumps.
I looked under the truck for anything unusual. I've got Monroe Reflex shocks that are 3-4 years old and found that I could recreate the clank sound by hitting against upper shock cover so that it contacts the shock body. Explains why it happens over certain bumps but I wonder why it just started.
I also noticed a 1/4 inch gap between the second and third leaves at the rear of the third. The third leaf was added in a couple of years ago. I don't remember if I've always had this gap or not but it's got me wondering.

Any thoughts on the pop, clank, and/or the spring gap?

 

Obviously it is suspension related.
Check closely the shock grommets where they mount to the frame and axle. When these wear out it will be metal to metal. Check also the spring and shackle mounting bushings as well as sway bar link bushings if equipped. You will need to look close and don't be shy using some force with your hand or a pry bar. I'll bet you'll find it.....good luck.............

It is rare but the spring pack bolt will sometimes shear or rust out allowing the spring pack to move around. This could also make some noise and needs to be repaired or a leaf can slip out.

 

I was driving downt the road one day when I heard a ping sound. Found out I had two of the leaf spring clamps pop off which caused the gap in the springs. it didnt affect the ride but they were gone. May seem dumb, but make sure they are still there.

But the sound may be totally different to why there is space there. Like you said it happens when you hit that particular spot, so its probably that.