Strange light bulb phenomenon
The coil is a resistor lets say its divided into three parts, they all have equal resistance (same material). If the coil in the bulb comes loose, it can short out at a different point. You have less resistance and more current through the same section of coil. This will make it brighter and also hotter and reduce the lifetime of the coil. 







simulate this circuit &ndash; Schematic created using CircuitLab