There are two issues in your question.
A big issue in your question is based upon what you call an observation!
When you say
observed - not deduced
, you highlight the whole issue of what you would consider being an observation.
In science, observations often take complex form. It is not only direct visual observation recorded on a standard camera. It is like asking for, recorded-on-camera evidence that quartz exist. Such evidence don't exist (and cannot exist), yet we know of their existence through other means of observation. It would make no sense for someone to only consider camera recording as valid mean of observation.
Of course, We have never recorded on a camera the evolution of an entire new organ because it takes a lot of time. Yet, evidences are numerous.
This technic of limiting arbitrarily the field of methods that one accepts to recognize as bringing evidence and call "observation" is a common technic from science denier (e.g. flat earth society, creationist). I made a similar point as the one I made here on this post if you want.
How to solve this "What is an observation" problem?
There is only one way to go. It will be for you to be able to understand the forms that observation can take. For this, you will have to learn a little bit about evolutionary biology and evolutionary genetics. For a very short introduction to evolutionary biology, you can have a look at Evo101 by UC Berkeley.
**A second issue is that it is unclear to know what **
It is hard to know what you would call a significant enough evolutionary event to be accepted. The risk is that you may define it large enough so that it fundamentally cannot be observed by a mean that you would accept.
For your curiosity, this post talks about evolution of lactose digestion in humans and this post about the evolution of cardio-vascular system.
Somewhat related post
You might want to have a look at post Is evolution a fact? and the link posts in the top voted answer.