See a sudden fire in your house, throw the most frequently abundant and readily-available fire supressant—water—on it. It's a natural, and generally sensitble, response.
Except when the fire is in a pan full of grease. See the video above for the result of that particular admixture. According to the Minneapolis Fire Department's Assistant Chief Cherie Penn, the department responded to three cooking-related conflagrations last Thanksgiving, one of which definitely started as a grease fire.
Here, courtesy of the department, are the steps to take if something catches fire on the stove, and you don't want to become part of Chief Penn's statistic this year.
1. TURN OFF the heat (burner), if safe to do so
2. COVER the pan with a tight-fitting lid, if safe to do so
If you can do these first 2 steps, the fire should go out. If the first 2 steps don't work, you can:
3. Use a FIRE EXTINGUISHER (which is basically baking soda under pressure, allowing you to smother the fire without getting too close like you'd have to do with a box of baking soda)
If none of the above works, CALL 911!
So why does water not actually work? The MFD explains:
NEVER USE WATER to extinguish a grease fire. Why not? Grease floats on water. When you add water to a grease fire, the water goes directly underneath the grease. The water then immediately explodes into hot steam, forcing the grease into the air in small droplets, which spontaneously combust when they hit the oxygen in the air outside of the pan. The result: HUGE FIRE BALL, which will most likely burn you and/or anything in it's path.