Technically a bull market occurs when the price of an asset consistently sets higher-highs and higher-lows for a sustained period of time. For this to take place there have to be more buyers than sellers in a market.
Bull markets are accompanied by a great deal of positive sentiment and expectation.
When a bullish market rises too quickly it’s a signal that people have become euphoric and that prices are becoming detached from reality. Bullish markets that rise too quickly tends to turn into bubbles.