Substance on roof rafters

I might have three right ups on this one. Insulation against flue, rafter being cut for installation of chase and not supported properly, and wanted to know what causes the crystal like substance on the rafter. In addition, shouldnt the rafter were it was cut and not supported be framed in with a header at mininum? The cut rafter is not attached to anything and just there. The span is mininum regardless I would like to see something supporting this.
How do you like the purlins? with or without support? How about ketchup?



James the crystal like substance is Sap

What causes the sap to the extent. High temperature in attic? Poor ventilation?

yes, this is the most likely cause