Both the Motor and ESC have limits relating to voltage .
Motor - will have a safe Max RPM . Putting more volts in at full throttle will push it past the limit . It will work , but , it will get hot and something will fail , like bearing , rotor or wires .
ESC - are built to handle a certain voltage . Putting more volts in , the ESC will shut down if it has an Over Voltage Protection feature or quickly fail due to too much voltage .
Have a look on the ESC sticker , usually they have something on there for operating voltage . And on the motor there might be a max rpm or at least a KV rating which will give you some idea of the safe voltage .
Do you have any pics you could post to identify the ESC or Motor ?