The consequences of a stock market bubble are generally recession and the need for more monetary stimulus. That increase in monetary stimulus means more money printing that may not stop until a recession, stock market crash, or both occurs.

Yes because the period of economic boom and stock market bubble during the 1920s is often referred to as the Roaring Twenties.

A stock market bubble can be defined as an economic cycle in which there is a rapid expansion, which is followed by contraction. Basically, too many investors become too eager to buy. When they realize the value of the stock is going down, and sell off to save some of their money. The crash usually happens because when there is a bubble, the investment class gets to a point when prices don't justify the underlying value.

Because... economics.

a crash-there's a major decrease in stock prices

a bubble-stock prices are higher than their real value

bull market-there's a general upward trend in stock prices