I have a wall in my house that we have been measuring our children on for years. Kids are grown now and we are relocating and i'm wondering if anyone knows how I could remove that section of drywall and keep it intact so I can frame it

Hi! I have an issue with a ceiling beam that I'm not sure how to tackle. Background might be helpful I suppose. I live in a co-op. Last year I had paint peeling in my bathroom. My roommate and I initially suspected water damage (there was a blister that contained moisture), but the super declared there was no sign of moisture other than the blister that we popped, and nothing was dripping. We scraped everything off and repainted. This year, as the temperature dropped and the heat was turned on, the bubbling came back. One of the regular maintenance guys came over and said it was water damage from above, and to confirm I was to feel the ceiling when the heat was on. If it was hot, then it was steam leaking from the radiator above. Sure enough, the ceiling was hot. They fixed it upstairs, and I'm slated to repaint my bathroom. A short while ago we got heating upgrades, and I heard that some units in my complex have suffered from cracked steam pipes. Last week I noticed a bubble on the beam of my living room, and initially figured the paint probably needed to be redone. Then today I looked up again and saw even worse (pics attached). I felt the beam, and there was a very slight warmth at the spot that was peeling, compared to the rest of the beam (which was cold). All the blisters visible in the pic are hollow when tapped, and some areas are, well, slightly spongy. I called the super, who came over to take a look, and declared there was no water/moisture since there were no stains, nothing wet, nothing dripping, etc..., and the slight warmth I was feeling was normal since there was a radiator in the floor above. At this point, I not too sure what to do. I can strip everything off and repaint, however I'm worried about steam leakage again, making the repaint a moot point without fixing the main problem. To make my paranoia worse, whenever the heat is on I hear a tapping/popping(?) coming from upstairs where the radiator is. Adding on top of that, there is a straight line, a slight shadow, on my wall stretching from the beam where the bubbling is, and along the way, tapping, spots here and there are hollow, and nowhere else. Is there anything I can do to find out what the root of the problem is? Any suggestions would be greatly welcome. Much thanks!