Question

Use the kinetic theory to explain,
When you come home from school and open the door you can smell your tea being cooked.

Answer 1

Tea is getting hot on the stove. 
2) As the tea and water gets hot, some combined molecules of tea and water will escape from the teapot. 
3) Those escaped molecules now have the entire free space of the entire room to float around in, which they do (because they have high kinetic energy due to being heated). 
4) Hence, in this scenario, your nose will detect a few of those molecules and you smell hot or warm tea. 
5) Cold tea would be a different story. Cold beverages like cold tea do not have the kinetic energy where molecules can 'break free' of the surrounding container. Someone could be sitting in the room having a can or bottle of cold tea and you would not notice that when you walked in the door.

Answer 2

It is Diffusion which is causing this not because the tea turns to gas as mentioned in the previous answer. It moves from a area of high concentration to low concentration.