So we pulled a grain bill for a barleywine several weeks ago but we use a 10gal mash tun which 27lbs of grain clearly wouldn't fit in with strike water. Ended up getting a second mash tun from a buddy and did a double mash and completely miscalculated our water volumes doing it that way (note: don't start a brew day after drinking a lot of beer and watching football).
We mashed in on the first one, waited 10min and started heating the strike water for the second and got that going about 20ish minutes later. After draining off and sparging the first one we started to drain off the second. Just after it finished we realized we had 10.5 gallons in the kettle for a 5 gallon batch. So clearly that one didn't get sparged. We ended up having to boil for 2.5hrs to get the volume back down to just over 6gal.
That was the longest most propane consuming single batch of beer I've ever done. Either way, all is well now and she has an OG of 1.105. It's going to get some bourbon soaked oak spirals in secondary and probably be forgotten about til, at the very earliest, late spring.
Long story short: I'm buying a large rectangular cooler for bigger beers in the future.