Hi Martin,
One such passage that comes to mind is Bhagavadgītā 11.44: priyāyārhasi
You can look at Oberlies,
A Grammar of Epic Sanskrit, which has a whole section on this phenomenon (pp. 34-49).
Pāṇini's
separation of the tripādī is important in formulating his rules to
avoid double sandhi, so you may also want to look into that side of
things (although I can't point you to specific scholarship off the top
of my head).
A typical commentarial response is to claim
'ārṣa' usage. Baladeva Vidyābhūṣaṇa, for example, writes on BhG 11.44:
priyāyārhasīti visargalopaḥ sandhiścārṣaḥ.