Sap to syrup: different options
As you may have learned, fresh sap is anywhere from 1-6% sugar, while finished syrup is ~66-67% sugar. To get from sap to syrup, producers remove lots of water from the sap, leaving the sugar and maple flavor behind. How do syrup producers remove all of this water? As you will learn here, there are a variety of different ways. This photograph shows how a kettle and open fire system were used in the past.
In most modern syrup producing operations, water is boiled off in an "evaporator". With an evaporator, a fuel source provides heat to boil the sap, and the concentrated syrup is collected.