What danger is posed by operating a boiler with insufficient water levels?

Operating a boiler with insufficient water levels presents significant dangers, primarily related to overheating and damage to the boiler. When the water level is low, the heat generated by the burner cannot be effectively transferred to the water, leading to excessive temperatures in the boiler’s metal components. This can result in thermal stress, warping, and ultimately failure of the boiler material.

As the heat continues to rise without adequate water to absorb it, the risk of a catastrophic failure, such as an explosion, increases markedly. This happens because pressurized steam can create explosive forces if it builds up in an overheated boiler that's not functioning properly.

Recognizing these dangers underscores the importance of maintaining proper water levels in a boiler system to ensure safe and efficient operation. Other options, while they may have some relevance in a broader operational context, do not encompass the critical dangers associated with low water conditions as clearly as the correct choice does.