Teacher: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
Teacher: Now, understand the problem? If you are still confused, see the following example:
 Magma rises from deep in the earth. The magma goes into volcanos. The volcanos pressure the magma upwards. The pressure causes the magma to push through the surface of the volcano. The lava cools. The lava forms new rock. New magma is pressured to the surface of the volcano. The volcano bursts through the rock the formed after the last eruption. 
Solution:  magma ,lava ,new rock 
Reason: The entities are present in the process paragraph and they undergo state change. So, this is a positive example.

Now, solve this instance: Add water to a pot. Put the pot over a source of heat. Turn the heat on. Wait for a few minutes. Begin to observe small bubbles in the water. Wait until the water starts to bubble a lot. Wait until you can see steam rising from the water. Turn the heat source off. Take the pot off of the heat source. 
Student:
water ,pot ,steam ,heat ,small bubbles ,boiling water 