St. Basil, Bishop of Kineshma reveals: "It happened in the province of Vyatka. A liturgy was being celebrated in the local church, and a crowd of communicants were waiting for the priest to leave the altar with the Holy Gifts. When the priest appeared with the Holy Chalice, he began, as usual, to read the prayer 'I believe, O Lord, and I confess,' which the believers repeated in unison. During the reading, the priest's attention was drawn to a particular tall man, who, especially loudly, shouted the words of prayer to the whole church. When communion began, this pilgrim also approached the Holy Cup, but after taking communion, he suddenly cried out loudly and stood on the left side in front of the icon of the Mother of God. The priest noticed that he spat something into his hand, and immediately sent the deacon to find out what was wrong, and if the Holy Gifts were in his hand, to take action against possible blasphemy. When the deacon approached the strange participant, then with amazement and horror I saw coal in his swollen hand. These were the burned holy gifts. The pilgrim’s mouth was also burned to such an extent that he could not close it from severe pain. It turned out that he was a schismatic, who decided to proceed with the sacrament of communion without first joining the Orthodox Church..."
A Life of St. Basil can be found here: The holy Basil, Bishop of Kineshma (catacombhistory.blogspot.com)