There is no rule that morpheme boundaries determine syllable boundaries. They are independent of each other. Rules of phonotactics and syllabification, however, do apply, like in all natural languages. Those rules alone determine what can constitute a syllable. Consequently, if two words differ only in the locations of morpheme boundaries, these words are pronounced in exactly the same way.
PMEG claims that it is possible and customary to demonstrate the morpheme boundaries in ambiguous words by dividing the words in syllables at the morpheme boundaries. But it does not tell how to do this:
Kiam oni volas elparoli kunmetitan vorton tre klare, aparte montrante la limojn inter la vortopartoj, oni nature uzas silabodividon laŭ tiuj limoj. La malofta kunmetaĵo konkludo (= ludo per konkoj) povas do soni kiel kon-klu-do en rapida elparolo, sed kiel konk-lu-do, kiam oni volas klare montri, kiel tiu vorto estas kunmetita. Kontraste la ofta vorto konkludo (= rezulto de rezonado) kredeble ĉiam sonas kiel kon-klu-do.
I suppose what is meant is that speakers can mark morpheme boundaries by inserting a break. In my opinion, this is not regular speaking of Esperanto. I would pronounce konklud'o and konk'lud'o absolutely identically. (I would not say konk'lud'o, in the first place, but konkoludo.) To insert a break at morpheme boundaries is an auxiliary device to make something explicit that normally isn't, in case it is requested, for example.