I had a batch recently where I missed my OG by a mile (off by .015! Bad crush, I think), and I didn't have time to boil it down to a proper concentration. I pitched yeast anyway, but when I sampled a few days in, it was clearly much too hoppy for the session beer I had inadvertently created. As a last ditch effort, I BIAB mashed 3 lbs of the same base malt on the stove with 3 quarts of water -- super thick mash, yielding a couple quarts of 1.105 wort, which I boiled for a couple of minutes, cooled and used to top off the original beer. Came out really good -- about the gravity I was shooting for, very crisp and tasty. Much better than I was expecting. Something to keep in mind, I guess!