Im a dentist and I will try to answer your question. Could the tube like substance be very thick, ropy, viscous saliva? That matches your description of not being able to see and it dissolving upon touch.
The most common causes for thick sticky saliva are a dry mouth:
-Dehydration, sinus infections, allergies, and dry mouth ( xerostomia) as a side effect of medications.
If you are taking a lot of medicine for various reasons, chances are that the dry mouth and thick saliva is due to the side effect of those medicines. Please visit the physician or doctor who has prescribed them, for alternatives, those that cause less of a dry mouth as a side effect.
What can you do now? In just two words, stay hydrated !
How do you do this:
I am going to list a number of things for you to start doing immediately:
1. Buy a cool mist humidifier to moisten your bedroom air, especially at night. (Be sure to keep the humidifier clean to avoid spreading bacteria or mold in the air.)
2.Drink 8 to 10 glasses of water a day, and take a water bottle with you when you leave home.
3.Suck on sugarless candy or chew sugarless gum to stimulate saliva. Lemon drops often work well.
4. Limit drinks with caffeine, like coffee, tea, colas, and chocolate.
5. Eat soft, moist foods that are cool or at room temperature. Try blenderized fruits and vegetables, soft-cooked chicken and fish, well-thinned cereals, popsicles, smoothies, and slushies. Avoid foods that stick to the roof of the mouth like peanut butter or soft bread.Take small bites, and chew your food well.
6.Avoid commercial mouthwashes, alcoholic and acidic drinks, and tobacco.
7. Moisten dry food using broth, soup, sauces, gravy, yogurt, or creams.
Give these seven steps at least 20 days to a month to work. if this has no effect whatsoever, then I suggest you visit the Oral Medicine department of the dental school nearest to you. A full assessment will be required to eliminate any underlying cause. Screening tests should be carried out to exclude hematinic (blood) deficiencies and to rule out diabetes. If all this is negative, there might be an underlying psychogenic cause(anxiety) for the dry mouth.
Hope this answers your question. Feel free to contact me again for more information. Please leave a positive rating for me if this answer has helped you. I do not get credit for it otherwise.
Good Luck !