This familiar video dramatically demonstrates what happens in a home fire. Essentially, the NFPA built a room inside of a test laboratory, and furnished it with mundane items from a bedroom: bed, dresser, lamp, chair, carpeting, curtains, and the like. A smoke detector was centered in the ceiling, a clock was mounted outside, and an electric heat coil was placed under the chair cushion, thereby simulating someone dropping a cigarette. Then they started the clock. The video shows wisps of smoke coming out, the wisps of smoke get bigger and bigger, the smoke beginning to collect at the ceiling, and then a flame starting.
Within two minutes, the fire reached the flashover point: i.e., the spontaneous ignition of hot smoke and gases. Within 70 seconds it set off the smoke detector in the room, and at some point thereafter, the temperature at the ceiling was around 500 degrees, and at the floor it was hot enough to boil water.