Hi Emma L.,
So, you probably want the bulk coefficient of thermal expansion for aluminum ~= 24 * 10^-6 C^-1 . Just multiply by the delta Temperature. That's a fractional result, so multiply by the original length to find the length increase. (We assume no extraordinary constructions that afford geometrical tricks, or tricky crystalline properties, etc. etc.)
Now, that was too easy! But now suppose the aluminum vat was extremely clean (i.e. free of the usual protective oxide layer). Now the boiling water can vigorously attack it (evolving hydrogen) -- and presently IT WILL BE NO LONGER (because it will have all reacted away)! So that's a kind of answer, too!
-- Cheers, -- Mr. d.