Tug - Bob gave a pretty good recap of suggestions previously made concerning this subject. Here's a few additional thoughts....
1) De-lamination is usually caused by the intrusion of water into the panel, so the first job is to attempt to find and fix the source. The wall insulation is frequently Styrofoam. Most walls are vacubonded and bonded with a water-soluble adhesive that won't "melt" the Styrofoam, as would a solvent based adhesive. Water intruding into the wall can dissolve the water-soluble adhesive, creating de-lamination.
2) If water has been in the wall for awhile, it's possible the insides have become so "rotted" that there's little or nothing left for the glue to cling to.
3) If both sides of the affected wall are accessible, it's also been suggested that it "might" work to drill a 1/4" hole clear through the wall, inject one of the commonly available expanding insulation foams, and put a bolt through the wall with a plywood square on each end and squeeze the bubble flat while the insulation foam cures.
We've heard price estimates of many thousands of dollars for professional repairs, so if the bubble is small and you're comfortable with DIY projects it's probably worth a try, because the problem is likely to get worse. Good luck. - Dave