All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
We do not know what the liquid that you are referring to is; the important thing is to know that the basic principle is that what comes out of the front or back passages is impure. Mawaahib Al-Jaleel reads, "It was narrated from the author of At-Talqeen and by Al-Qaraafi and others that whatever comes out of the two passages is impure."
Ablution is invalidated by the discharge of this liquid as well because any discharge that comes out of the front and back passages nullifies it.
Manaar As-Sabeel reads (in the chapter of the nullifiers of ablution), "The nullifiers which invalidate ablution are eight: whatever comes out of the front or back passages regardless of whether it be a significant or insignificant amount, and regardless of whether it is pure or impure..."
Az-Zaad reads, "Whatever comes out of the front or back passages invalidates ablution..."
For more information, please, refer to fatwa 82518.
As for the continued discharge of this liquid, it stops after thirty seconds - as you mentioned - then this is a short time, and you are required to wait until it ceases to come out and perform Istinjaa' (cleaning oneself with water after answering the call of nature) normally as you do after urinating.
In any case, you are not required to open the tip of the urethra to empty what is inside it.
Allah knows best.