The esterification reaction of salicylic acid with ethanol is performed in presence of dissolved 12-tungstophosphoric Brønsted-Lowry acid catalyst, a Keggin-type polyoxometalate (POM). The monitoring of the reaction with smell and the recovery of the catalyst with sight is presented. Formation of the sweet-scented ester is apparent from the smell. After the reaction, the dissolved POM catalyst is recovered via encapsulation into a metal-organic framework (MOF) made of copper nitrate and benzene-1,3,5-tricarboxylic acid (BTC), Cu[subscript 3](BTC)[subscript 2] (also called HKUST-1). The encapsulation causes a color change from a greenish liquid to a suspension of blue catalyst-containing particles. The catalyst can be recovered by filtration, dissolved in a new batch of reactants, and reused. The simplicity of this reaction and the accessibility of the catalytic chemistry to human senses, avoiding the need of analytical tools, make this reaction suitable for a classroom demonstration of catalysis for educational purposes.