Boiling a sample in a reagent is often used as a preparation step for many analyses. Typically is the determination of Protein/Nitrogen in the Kjeldahl method.
COD, Chemical Oxygen Demand, Trace Metal Analysis are other digestions where controlled conditions are important.
In the Kjeldahl method the sample is boiled in sulfuric acid together with salt and catalyst. This very reactive and corrosive mixture puts high demands on the materials used. Also a well designed fume removal system is necessary to avoid damages on the laboratory inventories. An Exhaust together with a Scrubber is often the solution for this.