One of the most known examples happened in Germany after WWII.
After the war Germany had lost quite a lot of businesses, infrastructure, industry and farming. Also obviously lots of manpower. Produce was scarce and inflation was extremely high, so it was actually quite difficult to purchase anything even though people had money. the Allied Forces introduced price control on almost all essential good in order to stop inflation. That obviously did not work at all and most goods were actually traded in the black market, so you could actually buy bread by paying with cigarettes.
A German economist, Ludwig Erhardt advised to remove all price and legal controls and to replace the old mark by a new one, but the Allied Forces only agreed to the latest, so a new currency was introduced, the Deutsche Mark, replacing the old Reichsmark. That had no effect whatsoever. However, Mr. Erhardt, from his position as Director of Economic Administration, decided unilaterally to remove of the price fixing and other regulations. And literally overnight, German streets filled with sudden and unplanned pop up markets, everyone started to sell anything they didn't need, just by the street or from their front yard.
In 1949 Erhardt became Minister of Economy for 14 years, and later, in 1963, Chancellor.