The particles in gases and liquids move more ... Once the flask stops being heated it cools and contracts. This causes the liquid to be sucked up the tube and into the flask.

Some premium tea bags might be leaving billions of microscopic plastic particles in your cup ... the tea and placed the empty teabags in water heated to 95C (203F), as if they were brewing ...

more expansable by heat than matter in the other two conditions ot liquid and solid. The reason is, that the particles of air or gas, far from being under the influence of cohesive attraction ...