Hi
Is anything evident on the soundtrack of these particular clips at the site of the pop, like a sharp peak?
If you play either clip in clip preview does it pop either at the start or finish? (i.e at the end they join together)
If you mute the two clips is there still a pop? (Shouldn't be!)
Select the first clip and then grab the right hand end of the clip and drag it to the left for about a second (in effect shortening the clip)
Select the second clip, grab the left end and drag it to the right for a second (in effect shortening the clip. Check there is no gap and then play the two clips. Does it still pop?
If you cut the clip as mentioned above any pop on the soundtrack should be eliminated.
Also zoom into the join and check you don't have a tiny portion another bit of clip left after trimming whose soundtrack might be playing for an instant.
Nat