I have found several different sources of data which show that a solution with a higher concentration of salt has a higher coefficient of volumetric thermal expansion than a lower concentration salt solution or distilled water. However there does not appear to be any explanation for this. How does a salt solution expand more than distilled water when both are heated over the same temperature range? Could it be related to specific heat capacity or convection?
See this data: https://publishing.cdlib.org/ucpressebooks/view?docId=kt167nb66r&chunk.id=d3_4_ch03&toc.id=ch03&brand=eschol%20