Lol. I agree. If you're at your pre-boil SG with way too much volume, then look for a small pot to boil the excess and make a small batch with it.
But most likely, you messed up the water calculations and you are under your SG. I've had that happen a couple times. You can either add the excess to the main boil until you reach your pre-boil volume and SG, or you can boil the excess in a separate pot and add it to the main pot when there is room. The only reason to do the second method is that you can boil it down to the proper volume faster due to boiling two separate pots.