darkwing_duck1
Vice Admiral
I just rewatched "In a Mirror, Darkly" and I'm pretty sure nothing "popped up." The beams seemed to eminate from ring surrounding the aft dome, just like the forward phasers seem to eminate from the ring surrounding the lower dome on the saucer.
It's hard to see through the glow, but it does seem like something is moving there just before they fire, but the beams do seem to be coming from the same location as the ball turrets on the TMP model.
I've seen orthos of the official mesh that Rob B posted some time ago, and there are definitely "nipples" on either side of the aft dome that are the phaser turrets.