One example from the Bible is Stephen, who was the first person to be killed for his faith in Christ. The Bible says that as he was being stoned to death, God gave him a glimpse of Heaven's glory. He declared, "I see heaven open and the Son of Man standing at the right hand of God" (Acts 7:56).
I believe God does grant a vision of Heaven to some people who are dying -- although it isn't common. My own maternal grandmother was said to have had an experience like this shortly before her death. Perhaps God does it to reassure the one who is dying, and also to challenge those who are left to be sure of their salvation. The Bible warns, "How shall we escape if we ignore such a great salvation?" (Hebrews 2:3).
Although such reports assure us of Heaven's reality, God has already given us all the evidence we need that Heaven is real. Death is the universal fate of every human being -- but by His resurrection from the dead Jesus Christ conquered all the forces of sin and death and Hell. Because He rose from the dead we can have hope -- hope of life with Him in Heaven forever.
Is your faith and hope in Christ? Do you know for sure that if you were to die tonight you would go to be with Christ forever? You can be, by turning from your sins and putting your faith and trust in Christ today.