Skimmers are notorious for going nuts at the most inopportune times, and sometimes for absolutely no discernible reason at all. This is made worse when the skimmate you have been collecting over a week or two suddenly overflows back into the sump. Suddenly you are left with a cabinet full of dirty bubbles! To offset the chance of this happening, empty and clean out your collection cup. If the skimmer does go bonkers, hopefully the collection cup won’t be full of crud.
If your skimmer if fitted with a drain off hose, run the hose to a bucket and leave the valve open. The hope is that the drain off will be able to counter the sudden over-skimming and prevent the dirty skimmate from re-entering the system.