I made maple syrup a couple weeks ago using sap from the trees in my backyard. I boiled it down, strained it and poured it into a glass jar. I put it in the fridge and ever since it has been hard as a rock! I wanted to use it on my pancakes tonight, If I can make it back to liquid is it okay to eat? I placed the jar in a bowl filled with hot water in hopes to make it back into liquid form. What happened that made this so hard?