Collecting Sap to Make Maple Syrup

Original post 3-20-14: The sap is running in our maple trees and I am collecting some to try to make maple syrup.  What an interesting exercise in working with colligative properties like boiling point elevation! I tried boiling down a little sap several years ago, but overshot the syrup stage to produce sugar.  To collect the sap, I drilled a hole in each tree to a depth of about 5-7 centimeters and angling somewhat upward into the tree.  For each spile, I used a (clean) plastic syringe and removed the plunger.  I cut the tip end off of the barrel with a razor blade, and then cut a sort of slit in the side of the barrel from the cut end until maybe a centimeter from the finger flange.  I inserted these spiles into the holes in the tree until only about a centimeter was showing (if you push too hard you might break the spile).  I oriented the finger flanges of each spile in a vertical position, which I used to wire on a one-gallon freezer bag with a zipper.  New post 4-13-14: I collected over 2 liters of sap (represented by the pitcher of water), which I boiled down to make about 100 mL of yummy maple syrup.  The whole process was fun, but it strikes me as quite energy intensive.