( ( A solution ) ( ( is ( ( ( a mixture ) ( of ( ( ( two or ) more ) substances ) ) ) ( that ( ( has ( the ( same composition ) ) ) throughout ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN solution)) (VP (VBZ is) (NP (NP (DT a) (NN mixture)) (PP (IN of) (NP (QP (CD two) (CC or) (JJR more)) (NNS substances))) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (NP (DT the) (JJ same) (NN composition)) (PP (IN throughout))))))) (. .)))
A solution is a mixture of two or more substances that  has the same composition throughout.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (NN type)) (PP (IN of) (NP (NN mixture))) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (NP (NP (DT the) (JJ same) (NN composition)) (PP (IN throughout) (NP (DT a) (NN solution))))))))) (. .)))