i don't know how, but it's the same with some wild fungal species (including edible mushrooms and small puffballs): a green field one day, and the next day covered in white fungi big enough to pick for eating -- one of nature's mysteries

it's what usually happens with shrooms when conditions are right -- temperature and  moisture are obviously important; however there could be other factors involved, such as light (they like some diffuse light, but the concensus is that they shouldn't be exposed to direct sunlight), CO2, substrate acidity, barometric pressure etc -- whatever it is, with most flushes one night they're all small, and the next morning they've doubled in size (both height and width)

i don't know whether they're communicating with each other, or whether it's because they're all clones and are therefore reacting the same way to external stimuli, or both -- (communication could be gaseous from the stems or caps, or it could be via the mycelial network) -- i've not seen any research on this, but it's probably out there somewhere