Why does the market become volatile close to expiry

Hello Everyone,
I am new to the derivatives market and would like to know why the indian market becomes volatile close to expiry? From what I have read my understanding is that here the derivative market is separated from the cash segment i.e. all future trades are settled in cash. So there should not be any arbitrage effects as well. My understanding may be wrong. Please correct me if I am wrong. Thanks in advance. Any help from seniors is highly appreciated..

Regards
dgplearner

Settling futures in cash doesn't imply that there are no arbitrage opportunities. You can still short a future and go long in stock (to take advantage of premium) or vice versa (for discount).
IMO, the volatility is due to the rollover of current month positions to next month ones. Say if this rollover is too much in favor of longs, the premium would increase creating arbitrage opportunity. Since the settlement is close, people would short futures and long stock to take advantage. Reverse for shorts. This would increase the volatility.
Seniors, correct me if I'm wrong .

In plain simple hindi .. "Diya bhujne se pehle bahut farfarata hai"