Why does exhaust pop when you give it gas?

Exhaust popping occurs when unburned fuel ignites in the exhaust system, typically due to a rich air-fuel mixture or incomplete combustion. This can happen when throttle is applied suddenly, causing a burst of fuel to enter the exhaust before it has fully burned. Additionally, modifications to the exhaust system, like removing catalytic converters or using less restrictive mufflers, can amplify this effect, leading to the characteristic popping sound.