What is the maximum temperature a boiling water can get without adding something in it any ingredient... if the water is heated in boiler what will be the maximum temperature a boiling water will attain and the maximum temperature of the steam in boiler?

Water boils at 100 degrees Celsius or 212 degrees Fahrenheit under standard conditions at sea level (at one atmosphere of pressure).

The boiling point of water and any other substance depends on the atmospheric pressure, which changes with elevation. At higher altitudes, the pressure is lower, and so water boils at a lower temperature. If the barometric pressure is not at the standard value, the boiling point will be different. For example, water boils at 72 degrees Celsius on Mount Everest.

WikiAnswers - What is the boiling point of water (http://wiki.answers.com/Q/What_is_the_boiling_point_of_water)

Changes in pressure will affect the boiling point.