I think your friend will be fine reducing the solution by boiling.
Salt-solutions can't be 'decomposed' at the temperature of boiling water, but prolonged boiling can form additional scum as oils'n'things combine with air.
βI sometimes marvel at how far Iβve come - blissful, even, in the knowledge that I am slowly becoming a well-evolved human being - only to have the illusion shattered by an episode of bad behaviour that contradicts the new and reinforces the old. At these junctures of self-reflection, I ask the question: βare all my years of hard work unraveling before my eyes, or am I just having an episode?β For the sake of personal growth and the pursuit of equanimity, I choose the latter and accept that, on this journey of evolution, I may not encounter just one bad day, but a group of many.β
β B.G. Bowers
ΰ₯