Joint "popping"

I could be wrong since you're talking about the shoulder joint, but generally whenever I "pop" or "crack" a joint, like my lower or upper back or hip joints it is a very good thing. I often crack a few upper back vertabrae on my first and second set of dips and I nearly always crack my lower back vertabrae during post training stretching. It gets everything into proper alignment.

I get some joint popping only when I do military press because of an old baseball injury. I tore my rotator cuff and my shoulders haven't been the save ever since. I just can't do some excercises. Maybe you should try some Smith machine shoulder presses or military instead of the dumbell???