You will be given a definition of a task first, then some input of the task.
You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.

Good question. Could be a number of reason, but my guess would be that you have some salt in your boiling water. When NaCl solution is placed in a flame the Na cation gets ionized and yellow light is given off. It doesn't take much salt for you to see this effect. You will see this even with regular tap water, since it also has a small amount of salts dissolved in it.
In fact, standard distilled water is usually not pure enough to avoid this effect. That's why chemist buy special stills to make ultrapure water for experiments.
Output:
Why does a Kitchen gas burner glow yellow when a pot of boiling water overflows?