Most of the coins that pump sometimes are as result of the activities of the so called whales in the market. That is why we see coins pump so easily even when it is not yet matured for that and as a result of this, they easily dump. I have seen situations where 24 hours coin pump with over 1000% profit for early investors. That is why care has to be taken when trading.
People often blame whales and they seem paranoid but the link shows that they really are manipulating the market and coins. It's really hard to crack down on them though.