Pour the needed amount of water in a microwave-safe measuring cup and place the cup inside the LG microwave oven.
Enter the cook time in minutes on the appliance keypad. For example, to boil two cups of water press "5."
Touch "Power Level" and press "1" followed by "0" to enter the power level of 10, which is the highest setting on an LG microwave.
Press "Start/Enter" to begin heating the water.
Insert a cooking thermometer into the water when the microwave stops. The water is at the boiling stage when the thermometer reads 100 degrees Celsius (212 degrees Fahrenheit).