Problem:
I am interested in identifying the maximum potential dissolved sucrose (%w/w) that plant sap could have, and which (biological, physical, chemical) factors constrain the observed sucrose concentrations.

For example, sugar maple has one of the highest sucrose contents at 6%, and the solution also contains fructose, glucose, organic acids, minerals (K, Ca, Mn, Zn, Na, Cl), amino acids, volatile organic compounds, phenols, enzymes, and most sap flow occurs when temperatures cross the freezing point each day.
Is there a way that I can calculate this theoretical maximum from "first principles" of organic- or bio-chemistry, or is this a question better suited for empirical study? Justify it.