Not sure that I ever have either - at least, nothing leaps immediately to mind - which is why I haven't contributed to this thread before. What counts as mystical?
Mysticism is one of those words for which there are probably many views about. One view is that it is not about seeking out experiences but stilling the mind or entering a still inner space. What arises tends to be indescribable and attempts to communicate it to others only give a sense of it, like formless, expansiveness, one-ness, overwhelming bliss, timelessness within which the individual consciousness is lost and found at the same time, a sense of enlivening and empowering. Because of its extreme nature it often gets called Heaven or God or Nirvana or Tao, Paradise, the Truth, Reality, Being, etc. Attempts to formalise it either mentally or physically tend to take one further from it. It is a mystery to be lived rather than a problem to be solved. Some example quotes:
Huang Po [9th C Ch. Zen Buddhist Master] Those who seek the truth by means of intellect and learning only get further and further from it. Not until your thoughts cease, not until you abandon seeking for something, not until your mind is as motionless as stone will you be on the right road to the Gate.
Bayazid al Bishtami [9th C Persian Sufi mystic] The contraction of hearts consists in the expansion of Self and the expansion of hearts in the contraction of Self.
Mechthild of Magdeberg [13th C German contemplative revelations] Whosoever should hold himself firmly in the pull which comes from God and follows after the light as he sees it, would come to such bliss and heavenly knowledge that no heart could contain it. Then he would be as an angel, ever lovingly united in God.
Hermes Tristmegistus [ 2nd C; Wisdom of Egypt Alchemist] The Good (or Pure Being) must be that which is devoid of all movement and all becoming, and has a motionless activity (effortless effort) that is centred within it; it lacks nothing nor is it assailed by perturbations, it is wholly filled with abundance of all that is desired. Anything that satisfied a need is called good; but the Good is that which is the source of all and satisfies all at all times.
Chuang-Tse [3rd C Taoist Authority] A motionless centre, wherefrom is seen nothing but infinity, which is neither this nor that, neither yes nor no.
Meister Eckhart [13th C German Dominican Theologian] The eye with which I see God, God sees me; my eye and God's eye is one eye, one seeing, one realising and one love.
Sri Sankaracharya [9th C Hindu Guru] How can there be knowledge or ignorance in Me who am eternal and always of the nature of Pure Conscious Being.
Sri Ramana Maharshi [d 1950 Hindu sage] The One Being the only Reality alone exists eternally. When even the ancient teacher Dakskinamurti revealed It through speechless eloquence, who else could have conveyed it by speech.