system
Given the following post, respond as if you're commenting on Reddit:
human
When a teabag/sugar is put into water heated up by microwave, the reaction is different to water heated up by a boiling kettle. Why?

If you heated water to boiling point by 2 different techniques, the reaction of putting a teabag/sugar into the cup is different.

Technique 1: Mug of water is microwaved to boiling point and then teabag or sugar is put in. In both cases, the water sizzles and turns cloudy, even as you mix it with a teaspoon.

Technique two: Water is boiled in a gas or electric kettle and then poured into a mug. A teabag or sugar is put in. The water remains clear even as you mix it with a teaspoon.

Why is there this difference?
gpt
When water is heated, it can hold less dissolved gas. In a boiling kettle,the agitation causes the excess gas to come out of solution. In the microwave the water heats and becomes supersaturated with gas, even after the water is no longer boiling (<100C). Your introduction of the tea bag provides nucleation points for dissolved gasses to come out of solution (like carbonated water in a chipped or dirty glass). 
Edit: corrected to "solution," not suspension.