What is the chemical principle of the "empty cup smoking" magic?

The magical principle of empty cup smoking;

Concentrated ammonia reacts with hydrochloric acid to produce ammonium chloride.

NH3*H2O + HCL == NH4CL + H2O

Performance steps:

Drop a little strong ammonia into the cup. Then use a dropper to extract a little hydrochloric acid. When playing, just drop the hydrochloric acid in the dropper into the cup. Concentrated ammonia water volatilizes ammonia, and concentrated hydrochloric acid volatilizes hydrogen chloride. When they meet in the air, they immediately react to generate ammonium chloride solid, and small solid particles disperse into the air to form white smoke, which is drilled out of the bottle mouth.