Complex sentence: Maple trees can be tapped by drilling holes into their trunks and collecting the exuded sap, which is processed by heating to evaporate much of the water, leaving the concentrated syrup.
Split into simpler sentences: Maple trees can be tapped by drilling holes into their trunks and collecting the exuded sap. The sap is processed by heating to evaporate much of the water, leaving the concentrated syrup.