I was cured of "pressonitis" years ago while flying VFR [no IFR] with the odd very broken and scattered cumulus, minding my own business at about 2000' [No high ground within MILES]. I started to descend gently to keep the ground clearly in sight and thought "Another 10 seconds of this and I'm turning back". About 6 seconds later ALL visual reference had gone. All I could think of as I started a turn was "How high are the wind turbines I know are round here somewhere?", while my sphincter gripped the seat.
All happened so fast it was terrifying. Looking back I could see NO dense cloud anywhere!